SOURCE: "Newton and Alchemy," in Occult and Scientific Mentalities in the Renaissance, edited by Brian Vickers, Cambridge University Press, 1984, pp. 315-35.

In the essay below, originally delivered as a lecture in 1982, Westfall discusses the proper weight critics should give to the influence of alchemy on Newton's scientific thought, specifically in his work on the concept of force in the natural world.

On the whole, Newton preferred not to publicize his involvement in alchemy. Unlike his other major pursuits, nothing of his alchemy, or at least nothing explicitly labeled as alchemy, appeared in print during his lifetime or in the years immediately following his death. A few people did know about it. A fascinating correspondence between Newton and John Locke following the death of Robert Boyle reveals that the three men, possibly the last three men from Restoration England whom one would have expected, only a generation ago, to...